Lubricant seals which are located around moveable shafts at the points they exit fluid-containing housings must be in good condition to function properly. This is particularly true for lubricant seals on internal combustion engines, such as the crankshaft seal. Such seals must be in good condition for trouble-free operation of vehicles. Undue wear, drying and cracking of seals can result in leakage of fluids from the crankcase or other housings and even lead to increased wear of internal moving parts.
Therefore, seals are frequently changed. But changing lubricant seals, particularly crankcase seals, can be a time-consuming and troublesome operation. For certain type of work vehicles, such as tractors, road graders and the like, which are typically exposed to a significant amount of dust, dirt and grit in their normal operation, such seals must be changed as often as two or three times before a general overhaul of the crankcase parts is required. In an ideal situation, of course, such seals would require changing only at the time a general overhaul is required.
Lubricant seals of the type located around movable shafts where they exit fluid-containing housings undergo degradation and wear. Such seals are typically made of rubber, neoprene, a synthetic material known as Viton (a Dupont trademark), or leather, or a variety of other suitable materials. The inside surfaces of such lubricant seals are in contact with fluid within the housings on which they are mounted, but the outside surfaces are typically in contact with the often very dirty environment in which the equipment is operating. Thus, while the fluid in the housing can serve to preserve the inside surfaces of such seals, the outside surfaces have no preserving fluid in contact with them. The outside surfaces are much more susceptible to drying, cracking and other degradation, whether such degradation occurs because of heat, dryness, or a combination thereof.
Drying of the outside surface of the seal results in an accelerated wear of the seal. Furthermore, over a period of time a hardened seal can cause wear on the shaft turning or reciprocating within such seal.
In addition, the outside surface and the seal edge in contact with the shaft exiting the fluid-containing housing are exposed to dust, dirt and grit. This is particularly true for crankcase seals on farm tractors, construction vehicles, and road-building equipment, all of which frequently operate in a dusty environment.
Such dirt can cause a roughness in the contact between the seal and a rotating or reciprocating shaft and such roughness can wear grooves in the shaft. Such grooves can in themselves cause wear or unevenness of wear on the seal (or a subsequently installed seal) and lead an early need for seal replacement.
In short, there is a need to improve the life of lubricant seals of the type around movable shafts where such shafts exit their fluid-containing housings. In particular, there is a need to improve the life of lubricant seals on crankcases or internal combustion engines.